Composite semipermeable membrane, production method thereof, and water treatment method using the same

ABSTRACT

A composite semipermeable membrance of the present invention comprises a thin film and a porous support membrane supporting the thin film, wherein the thin film includes polyamide based resin having a constituent unit with amide bond between diamine residue and di or tri carboxylic acid residue, in which nitrogen atom of the amide bond has a substituent of aromatic ring. A production method of this invention includes a contacting step of contacting the above composite semipermeable membrane with solution including an oxidizer. In addition, a water treatment method of this invention comprises a step of separating a raw water by a composite semipermeable membrane to obtain permeation water in which salt and/or organic substance is removed sufficiently in practical use, characterized in that the composite semipermeable membrane of this invention is used and a fungicide is added into the raw water. 
     This invention provides a composite semipermeable membrane having practically permeability, and excellent desalting faculty and oxidizer resistance, a production method thereof, and water treatment method using the same.

This application is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application PCT/JP02/02 165, filed Mar. 8, 2002, whichclaims priority to Japanese Patent Application Nos. 2001-78490 filedMar. 19, 2001, 2001-81827 filed Mar. 22, 2001, 2001-368578 filed Dec. 3,2001, 2001-368584 filed Dec. 3, 2002, and 2002-26767 filed Feb. 4, 2002,respectively. The International Application was not published under PCTArticle 21(2) in English.

BACKGROUND ART

1. Technical Field

The present invention relates to a composite semipermeable membrane forseparating a component of a liquid mixture selectively, a method forproducing the same, and a water-treating method using the compositesemipermeable membrane. The present invention particularly relates to acomposite semipermeable membrane comprising a thin film made mainly of apolyamide on a porous base material and having practical water flux,desalting faculty and endurance, and a water-treating method using thecomposite semipermeable membrane.

2. Technical Background

As semipermeable membranes used for purposes described above, there areknown asymmetrical membranes wherein asymmetrical structures are made ofthe same material by a phase-separating method and compositesemipermeable membranes wherein a thin film which is made of differentmaterials and has a selective separability is formed on a porous basematerial.

As the latter semipermeable membranes, suggested are a great number ofcomposite semipermeable membranes wherein a thin film made of apolyamide obtained by interfacial polymerization of a polyfunctionalaromatic amine and a polyfunctional aromatic acid halide is formed on aporous base material (for example, JP-A Nos. S55-147106, S62-121603,S63-218208, H2-187135, and so on). Suggested are also compositesemipermeable membranes wherein a thin film made of a polyamide obtainedby interfacial polymerization of a polyfunctional aromatic amine and apolyfunctional alicyclic acid halide is formed on a porous base material(for example, JP-A No. S61-42308, and so on).

In order to improve the water flux of the above-mentioned compositesemipermeable membranes further, additives are suggested. There areknown substances capable of removing hydrogen halide generated byinterfacial reaction, such as sodium hydroxide or trisodium phosphate;known acylating catalysts; compounds for decreasing the interfacialtension on a reaction field at the time of interfacial reaction; and soon (for example, JP-A Nos. S63-12310, H6-47260, H8-224452 and so on).

For these semipermeable membranes, endurance such that various oxidizerscan be resisted, in particular, washing with chlorine can be resisted isdemanded in light of more stable operability in various water treatmentplants, a typical example of which is a water-producing plant, andpursuit of low costs based on prolongation of the lifespan of themembranes. It is said that the polyamide-based semipermeable membranesexemplified above have practical oxidizer resistance. It is not,however, said that all of them have resistance having such a level thatconstant or intermittent chlorine-sterilization can be resisted for along time. It is therefore desired to develop semipermeable membraneshaving both of a higher oxidizer resistance and practical water flux anddesalting faculty.

For these purposes, suggested are a composite membrane obtained from adiamine having only a secondary amino group (JP-A No. S55-139802), acomposite membrane obtained using an aliphatic diamine or alicyclicdiamine (JP-A Nos. S58-24303, S59-26101, S59-179103, H1-180208, andH2-78428), a composite membrane having a diphenylsulfone structure (JP-ANos. S62-176506, S62-213807 and S62-282603), a membrane to which achlorine-resistance is given by post-treatment (JP-A No. H5-96140), andso on.

However, these membranes do not have water flux, desalting faculty oroxidizer resistance which are required for practical semipermeablemembranes. Thus, higher properties are demanded. In other words, it isknown that in polyamide based reverse osmotic membranes, polyamidesobtained using an aliphatic diamine whose main chain does not anyaromatic ring are superior in oxidizer resistance, as described above,but the desalting faculty and water flux of the reverse osmoticmembranes are not sufficiently satisfied.

The above-mentioned JP-A No. H1-180208 discloses a production processcomprising the step of immersing a polyamide based compositesemipermeable membrane obtained using both a polyfunctional aromaticamine and an aliphatic diamine into an aqueous chlorine-containingsolution having a pH of 6 to 13. However, the publication never suggestswhat kind of other composite semipermeable membranes this process can beapplied to.

Thus, an object of the present invention is to provide a compositesemipermeable membrane having both practical water flux and superiordesalting faculty and oxidizer resistance, a method for producing thesame, and a water-treating method which makes it possible to exhibitpractical water flux and superior desalting faculty and oxidizerresistance, using the same.

DISCLOSURE OF THE INVENTION

The inventors made eager investigations repeatedly to attain theabove-mentioned object. As a result, the inventors have found out thatby causing a polyamide base resin for forming a thin film to have anaromatic ring in a substituent on the nitrogen atom in the amide bondthereof, the resin has a higher desalting faculty than resins whereinsuch a substituent is an alkyl group and resins not having such asubstituent. The inventors have also found out that by bringing acomposite semipermeable membrane having such a thin film into contactwith an aqueous oxidizer solution, water flux can be drasticallyimproved without lowering the performance of blocking various solutes.Thus, the present invention has been made.

That is, a composite semipermeable membrane of the present invention isa composite semipermeable membrane comprising a thin film and a poroussupport membrane for supporting this, characterized in that the thinfilm comprises a polyamide based resin having a constituent unitrepresented by the following general formulas (I) and/or (II):

wherein R₁₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₁₂ and R₁₃ each independently represent anaromatic hydrocarbon group which may have a substituent, or a hydrogenatom, at least one of R₁₂ or R₁₃ represents an aromatic hydrocarbongroup which may have a substituent, and R₁₄ represents a bivalentorganic group, and

wherein R₂₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₂₂ and R₂₃ each independently represent anaromatic hydrocarbon group which may have a substituent, or a hydrogenatom, at least one of R₂₂ or R₂₃ represents an aromatic hydrocarbongroup which may have a substituent, and R₂₄ represents a trivalentorganic group.

A composite semipermeable membrane of the present invention ispreferably a composite semipermeable membrane comprising a thin film anda porous support membrane for supporting this, wherein the thin filmcomprises a polyamide based resin having a constituent unit representedby the following general formulas (Ia) and/or (IIa):

wherein R₃₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₃₂ and R₃₃ each independently represent aphenyl group, or a hydrogen atom, at least one of R₃₂ or R₃₃ representsa phenyl group, and R₃₄ represents a bivalent organic group, and

wherein R₄₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₄₂ and R₄₃ each independently represent aphenyl group, or a hydrogen atom, at least one of R₄₂ or R₄₃ representsa phenyl group, and R₄₄ represents a trivalent organic group.

A composite semipermeable membrane of the present invention ispreferably a composite semipermeable membrane comprising a thin film anda porous support membrane for supporting this, characterized in that thethin film comprises a polyamide based resin having a constituent unitobtained by condensation reaction of a diamine component represented bythe following general formula (III) and a polyfunctional acid halidehaving 2 or more valences.

wherein R₅₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₅₂ and R₅₃ each independently represent anaromatic hydrocarbon group which may have a substituent, or a hydrogenatom, at least one of R₅₂ or R₅₃ represents an aromatic hydrocarbongroup which may have a substituent.

The method for producing a composite semipermeable membrane of thepresent invention comprises a contact step of bringing any one of theabove-mentioned composite semipermeable membranes into contact with anaqueous oxidizer solution. Another composite semipermeable membrane ofthe present invention is a membrane obtained by this production process.

The water-treating method of the present invention is a water-treatingmethod of subjecting water containing a salt and/or an organicsubstance, as raw water, to membrane-separation treatment with acomposite semipermeable membrane to obtain permeation water wherein thesalt and/or the organic substance is/are sufficiently removed inpractice, characterized in that as the composite semipermeable membrane,any one of the above-mentioned composite semipermeable membranes isused, and further a fungicide is added to the raw water.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a graph showing a change in salt-blocking rate with thepassage of time in Examples 1–3 and Comparative Examples 1–5.

BEST EMBODIMENTS FOR CARRYING OUT THE INVENTION

Best embodiments for carrying out the present invention will bedescribed hereinafter.

[Composite Semipermeable Membrane]

The composite semipermeable membrane of the present invention is acomposite semipermeable membrane comprising a thin film and a poroussupport membrane for supporting this, characterized in that the thinfilm comprises a polyamide based resin having a constituent unitrepresented by the above-mentioned general formulae (I) to (IIa). Thecomposite semipermeable membrane is also characterized in that the thinfilm comprises a polyamide based resin having a constituent unitobtained by condensation reaction of a diamine composition representedby the above-mentioned general formulae (III) to (IIIa) and apolyfunctional acid halide having bivalent or more.

R₁₁, R₂₁, R₃₁, R₄₁, R₅₁ and R₆₁, in the general formulae (I) to (IIIa)each represent an alkylene group which has 2 to 10 carbon atoms and maycontain —O—, —S—, or —NR—, wherein R represents a hydrogen atom or alower alkyl group (having 1 to 4 carbon atoms). Specific examplesthereof include —C₂H₄—, —C₃H₆—, —C₄H₈—, —C₅H₁₀—, —C₆H₁₂—, —C₇H₁₄—,—C₈H₁₆—, —C₉H₁₈—, —C₁₀H₂₀—, —CH₂OCH₂—, —CH₂OCH₂OCH₂—, —C₂H₄OCH₂—,—C₂H₄OC₂H₄—, —CH₂SCH₂—, —CH₂SCH₂SCH₂—, —C₂H₄SCH₂—, —C₂H₄SC₂H₄—,—C₂H₄NHC₂H₄—, and —C₂H₄N(CH₃)C₂H₄—. Alkylene groups which do not containany heteroatom are particularly preferred from the viewpoints of afurther improvement in oxidizer resistance, reactivity at the time offorming a film, the desalting faculty of the formed film, and so on.

R₁₂, R₁₃, R₂₂, R₂₃, R₃₂, R₃₃, R₄₂, R₄₃, R₅₂, R₅₃, R₆₂ and R₆₃ are eachindependently an aromatic hydrocarbon group which may have asubstituent, or a hydrogen atom. However, at least one of R₁₂ or R₁₃ isan aromatic hydrocarbon group which may have a substituent. The samematter is also applied to the other combinations. Specific examplesthereof include H, —C₆H₅, —CH₂C₆H₅, —C₆H₄OH, —C₆H₄CH₃, —C₆H₄NO₂, and—C₆H₄Cl. From the viewpoints of water flux of the formed film, desaltingfaculty, and so on, a phenyl group which may have a substituent ispreferred, and —C₆H₅ is particularly preferred. Accordingly, at leastone of R₃₂ or R₃₃ is preferably —C₆H₅, and only one thereof is morepreferably —C₆H₅. The same matter is also applied to R₄₂ or R₄₃.

In the present invention, the above-mentioned diamine component ispreferably a compound represented by the following general formula(IIIa):

wherein R₆₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₆₂ and R₆₃ are each independently a phenylgroup or a hydrogen atom, and at least one of R₆₂ or R₆₃ is a phenylgroup.

R₁₄, R₂₄, R₃₄ and R₄₄ in the general formulas (I) to (IIa) are each abivalent or trivalent organic group, and correspond to a residue groupof a polyfunctional acid halide which has two or more valences and formsthe thin film of the present invention by condensation reaction with thediamine component represented by the general formula (III) or (IlIa).The polyfunctional acid halide is not particularly limited. Examplesthereof include propanetricarboxylic acid chloride, butanetricarboxylicacid chloride, pentanetricarboxylic acid chloride, glutaryl halide,adipoyl halide, cyclopropanetricarboxylic acid chloride,cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acidchloride, cyclopentanetetracarboxylic acid chloride,cyclohexanetricarboxylic acid chloride, tetrahydrofurantetracarboxylicacid chloride, cyclopentanedicarboxylic acid chloride,cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acidchloride, and tetrahydrofurandicarboxylic acid chloride. From theviewpoints of reactivity, the desalting faculty of the formed film, thewater flux thereof and so on, polyfunctional aromatic acid halides arepreferred. Examples of such polyfunctional aromatic acid halides includetrimesic acid chloride, trimellitic acid chloride, terephthalic acidchloride, isophthalic acid chloride, pyromellitic acid chloride,biphenyldicarboxylic acid chloride, naphthalenedicarboxylic aciddichloride, benzenetrisulfonic acid chloride, benzenedisulfonic acidchloride, and chlorosulfonylbenzenedicarboxylic acid chloride.

The polyamide base resin in the present invention preferably has acrosslink structure. In this case, a polyfunctional acid halide havingtrivalent or more is preferably used. In the case of using thepolyfunctional acid halide having three or more valences, thecrosslinked moiety thereof is made of a constituent unit represented bythe general formula (II). In the case that a non-crosslinked moiety ispresent, it is made of a constituent unit represented by the generalformula (I) and R₁₄ is made of a bivalent organic group in which acarboxylic group or a salt thereof remains. The same matter is appliedto relationship between the general formula (IIa) and the generalformula (Ia).

The polyamide based resin which makes the above-mentioned film may be ahomopolymer, or a copolymer containing a plurality of theabove-mentioned constituents units or a different constituent unit, or ablend comprising a plurality of the homopolymers. Examples thereofinclude polyamide based resins having the constituent unit representedby the general formula (I) and having the constituent unit representedby the general formula (II). Examples of the different constituent unitinclude a diamine component containing, in its main chain, an aromaticring, a diamine component containing, in its side chain, no aromaticring, and other diamine components used in polyamide based semipermeablemembranes.

The polyamide based resin in the present invention comprises theconstituent unit(s) represented by the general formulas (I) and/or (II)or the general formulas (Ia) and/or (IIa) preferably at a ratio of 50%or more by mole, more preferably at a ratio of 80% or more by mole. Ifthe ratio is less than 50% by mole, the effect of the aromatic ring inthe substituent on the nitrogen atom of the amide bond becomes small sothat practical water flux and superior desalting faculty and oxidizerresistance trend not to be simultaneously satisfied.

The thickness of the thin film (separation active layer) in the presentinvention, which depends on the process for producing the thin film, ispreferably from 0.01 to 100 μm, more preferably from 0.1 to 10 μm. Asthe thickness is smaller, a better result is caused from the viewpointof permeation flux. However, if the thickness is too small, mechanicalstrength of the thin film lowers so that defects are easily generated.Thus, a bad effect is produced on the desalting faculty.

The porous support membrane for supporting the thin film in the presentinvention is not particularly limited if it can support the thin film.Examples thereof include films of various substances such aspolysulfone, polyarylether sulfone such as polyether sulfone, polyimideand polyfluoride vinylidene. In particular, from the viewpoints ofchemical, mechanical and thermal stabilities a porous support membranemade of polysulfone or polyarylether sulfone is preferably used. Such aporous support membrane usually has a thickness of about 25 to 125 μm,and preferably has a thickness of about 40 to 75 μm. However, thethickness is not necessarily limited to such a thickness.

The porous support membrane may have a symmetrical structure or anasymmetrical structure. However, the asymmetrical structure is preferredto satisfy both of the supporting function of the thin film andliquid-passing property. The average pore size of the thin film formedside of the porous support membrane is preferably from 1 to 1000 μm.

When the thin film in the present invention is formed on the poroussupport membrane, the method thereof is not limited at all. Any knownmethod can be used. Examples thereof include interfacial condensation,phase separation and thin-film coating methods. Particularly preferredis an interfacial condensation method of applying an aqueous solutioncontaining a diamine component onto the porous support membrane and thenbringing the porous support membrane into contact with a nonaqueoussolution containing a polyfunctional acid halide to form a thin film onthe porous support membrane. Details of conditions and so on of thisinterfacial condensation method are described in JP-A Nos. S58-24303,H1-180208 and so on. These known techniques can be appropriatelyadopted.

In order to make the film-formation easy or improve the performance ofthe resultant composite semipermeable membrane, various reagents can becaused to be present in the reaction field. Examples of the reagentsinclude polymers such as polyvinyl alcohol, polyvinyl pyrrolidone andpolyacrylic acid; polyhydric alcohols such as sorbitol and glycerin;amine salts such as salts of tetraalkylammonium halide ortrialkylammonium and an organic acid, which are described in JP-A No.2-187135; surfactants such as sodium dodecylbenzenesulfonate, sodiumdodecylsulfate and sodium laurylsulfate; sodium hydroxide, trisodiumphosphate, triethylamine and camphorsulfonic acid, which can removehydrogen halide generated by condensation polymerization reaction; knownacylating catalysts; and compounds having a solubility parameter of 8 to14 (cal/cm³)^(1/2), which are described in JP-A No. 8-224452.

[Method for Producing a Composite Semipermeable Membrane]

The following will describe the production method of the presentinvention. The method for producing a composite semipermeable membraneof the present invention is characterized by comprising a contact stepof bringing a composite semipermeable membrane as described above intocontact with an aqueous oxidizer solution.

The used oxidizer is a substance which usually has oxidizing effect, andis not limited at all if it is generally used in the form of an aqueoussolution. Examples thereof include permanganic acid, permanganates,chromic acid, chromate, nitric acid, nitrates, peroxides such ashydrogen peroxide, sulfuric acid, hypochlorites, and hypobromites. Fromthe viewpoints of costs, handling performance and so on, hypochlorite,in particular, sodium hypochlorite is preferred.

The production method of the present invention preferably comprises thestep of bringing a composite semipermeable membrane described above intocontact with an aqueous oxidizer solution containing a metal salt. Bycatalytic effect of the metal salt, the time for the contact with theabove-mentioned oxidizer solution can be made short. Examples of themetal salt used herein may be alkali metal salts, alkali earth metalsalts, and transition metal salts, and include lithium chloride,potassium chloride, magnesium chloride, magnesium nitrate, calciumnitrate, iron chloride, copper chloride and calcium chloride. Metalchlorides are preferred.

The concentration of the metal salt in the aqueous solution is decidedin light of the effect of increasing permeation flux by contact in ashort time. For example, in the case that sodium hypochlorite is used asthe oxidizer, the concentration thereof can be set to 0.001 to 50% byweight, preferably 0.05 to 5% by weight. If the concentration of theinorganic salt is less than 0.001% by weight, a time required forobtaining desired effects is too large. Thus, such a concentration isnot practical in the production. Alternatively, desired effects cannotbe obtained within a time permissible in the production. If theconcentration of the inorganic salt is more than 50% by weight, adeterioration in the film, such as a decrease in the desalting facultyof the composite film, is unfavorably caused.

In the present invention, as the method for bringing the aqueousoxidizer solution into contact with the composite film, all methods suchas immersion, solution-transmitting under applied pressure, spray,coating and showering can be given as examples. In order to givesufficient effects by the contact, immersion under normal pressure orsolution-transmitting under applied pressure is preferred. Specifically,it is advisable to perform a method of immersing the compositesemipermeable membrane to the aqueous oxidizer solution under normalpressure, or a method of transmitting the aqueous oxidizer solution tothe composite semipermeable membrane under applied pressure.

When the contact of the aqueous oxidizer solution is performed by theimmersion under normal pressure or the solution-transmitting methodunder applied pressure, the concentration of the oxidizer in thisaqueous solution can be decided in light of desired effects. Forexample, in the case that sodium hypochlorite is used as the oxidizer,the concentration thereof can be set to 1 mg/L to 10%, preferably 10mg/L to 1% as a free chlorine concentration. If the free chlorineconcentration is less than 1 mg/L, a time required for obtaining desiredeffects is too large. Thus, such a concentration is not practical in theproduction. Alternatively, desired effects cannot be obtained within atime permissible in the production. If the free chlorine concentrationis more than 10% by weight, a deterioration in the film, such as adecrease in the desalting faculty of the composite film, is unfavorablycaused.

When the contact of the aqueous oxidizer solution is performed, thecontact temperature is also decided in light of the effect of increasingpermeation flux by contact in a short time. For example, in the casethat sodium hypochlorite is used as the oxidizer, the concentration canbe set to 5 to 60° C., preferably 25 to 60° C. If the contacttemperature is less than 5° C., a time required for obtaining desiredeffects is too large. Thus, such a temperature is not practical in theproduction. Alternatively, desired effects cannot be obtained within atime permissible in the production. If contact temperature is more than60° C., a deterioration in the film, such as a decrease in the desaltingfaculty of the composite film, is unfavorably caused.

When the contact of the aqueous oxidizer solution is performed by theimmersion under normal pressure or the solution-transmitting methodunder applied pressure, the contact time is not limited at all and canbe set to an arbitrary time if it gives desired effects and is within arange permitted by restriction in the production.

When the contact of the aqueous oxidizer solution is performed by thesolution-transmitting method under applied pressure, the pressure forsupplying this aqueous solution to the composite film is not limited atall within a range permitted by physical strengths of the compositefilm, and a member and equipment for giving the pressure. The contactcan be performed within the range of, for example, 0.01 MPa to 10 MPa.

When these treatments, that is, the immersion under normal pressure andthe solution-transmitting method under applied pressure are performed,the shape of the composite film is not limited at all. In other words,the treatments can be conducted using all film shapes which can beconsidered, such as a flat film shape or a spiral element form.

[Water-treating Method Using the Composite Semipermeable Membrane]

The composite semipermeable membrane of the present invention has acharacteristic of improving oxidizer resistance to a great extent.Therefore, in the method of subjecting raw water containing a saltand/or an organic substance to membrane-separation treatment with thiscomposite semipermeable membrane to obtain permeation water wherein thesalt and/or the organic substance is/are sufficiently removed inpractice, an oxidizer having an effect as a fungicide is added to theraw water and then water treatment can be performed. Moreover, by thegreat improvement in oxidizer resistance, water treatment can besuitably performed even when the fungicide is present, at aconcentration having a sufficient sterilizing effect, in the permeationwater undergoing the membrane-separation treatment.

The oxidizer may be added constantly or intermittently during the watertreatment operation by means of the composite film. The addition may beperformed by stopping the water treatment operation and sealingcomposite film modules with the raw water containing the oxidizer for agiven time.

According to the oxidizer, the effect of suppressing contamination ofthe film can be expected by the sterilizing effect thereof. Examplesthereof include hypochlorites such as sodium hypochlorite and calciumhypochlorite, hydrogen peroxide water, sulfuric acid, and nitric acid.From the standpoints of sterilizing effect and handling performance,hypochlorites such as sodium hypochlorite is preferably used. In thecase that the oxidizer is added to the raw water in this way, the pH ofthe solution may be adjusted or may not be adjusted.

The water-treating method of the present invention can be suitably usedfor purposes for giving advantages such that contamination of the filmis suppressed by incorporating the oxidizer having sterilizing effectinto the raw water. Examples thereof include sterilization of an asepticwater system, removal of activated carbon from a drinking-waterproducing system, disposal of waste of liquid for washing container orthe like, and a system for cleaning up water in a pool. However, thepurposes are not limited to these examples. In the case that the rawwater in the water-treating method is waste liquid after a drinkingwater container is washed with washing liquid, the present invention isparticularly effective since the sterilization with the oxidizerproduces a large effect of heightening the stability of the watertreatment.

According to the water-treating method of the present invention,practical water flux and superior desalting faculty can be exhibitedsince the composite semipermeable membrane of the present invention isused. Moreover, the film also has oxidizer resistance; therefore, watertreatment can be performed in the state that a fungicide is added to theraw water. At this time, by the addition of the fungicide, contaminationof the film is suppressed by the sterilizing effect so that thedurability and the maintainability of membrane-separation becomeparticularly good.

EXAMPLES

The following will describe Examples demonstrating the structure and theeffects of the present invention.

Example 1-1

An aqueous solution containing 3% by weight of N-phenylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.2% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking the salt was 99.3%. The permeationflux was 0.32 m³/(m²·day). Under the same conditions, a test aboutammonium nitrate was made. As a result, the blocking rate was 95.0%.

This membrane was immersed into an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 100 mg/L. After 100 hours, testswere made under the same conditions. As a result, the rate of blockingsalt was 99.0%, and the permeation flux was 0.38 m³/(m²·day). The rateof blocking ammonium nitrate was 94.0%.

Example 1-2

An aqueous solution containing 4% by weight of N-phenylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isoparaffin based mixed solution(IP Solvent, made by Idemitsu Petrochemical Co., Ltd.) containing 0.25%by weight of trimesic acid chloride was brought into contact with thesurface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 98.9%. The permeation fluxwas 0.33 m³/(m²·day). Under the same conditions, a test about ammoniumnitrate was made. As a result, the blocking rate was 95.3%.

This membrane was immersed into an aqueous sodium hypochlorite having afree chlorine concentration of 100 mg/L. After 100 hours, tests weremade under the same conditions. As a result, the rate of blocking saltwas 99.5%, and the permeation flux was 0.41 m³/(m²·day). The rate ofblocking ammonium nitrate was 95.7%.

Comparative Example 1-1

A composite semipermeable membrane was produced and tests were made inthe very same way as in Example 1-1 except that the diamine componentwas changed to m-phenylenediamine. The results are shown in Table 1.Performances of the membrane wherein m-phenylenediamine was used as theamine component in this way were markedly lowered by immersing themembrane into the aqueous sodium hypochlorite solution.

Comparative Example 1-2

A composite semipermeable membrane was produced and tests were made inthe same way as in Example 1-1 except that the diamine component waschanged to ethylenediamine. The results are shown in Table 1. Thepermeation flux of the membrane wherein ethylenediamine was used as theamine component in this way was insufficient.

Comparative Example 1-3

A composite semipermeable membrane was produced and tests were made inthe very same way as in Example 1-1 except that the diamine componentwas changed to N-methylethylenediamine. The results are shown inTable 1. About the membrane wherein N-methylethylenediamine was used asthe amine component in this way, the rates of blocking salt and ammoniumnitrate were insufficient.

Comparative Example 1-4

A composite semipermeable membrane was produced and tests were made inthe very same way as in Example 1-1 except that the diamine componentwas changed to N-ethylethylenediamine. The results are shown in Table 1.About the membrane wherein N-ethylethylenediamine was used as the aminecomponent in this way, the rates of blocking salt and ammonium nitratewere insufficient.

TABLE 1 Before After immersion immersion Ammonium Ammonium No. Saltnitrate Salt nitrate Example 1 Blocking rate (%) 99.3 95.0 99.0 94.0Permeation flux 0.32 — 0.38 — (m³/m²/d) Example 2 Blocking rate (%) 98.995.3 99.5 95.7 Permeation flux 0.33 — 0.41 — (m³/m²/d) Compara- Blockingrate (%) 99.5 98.8 95.3 76.0 tive Permeation flux 1.23 — 4.45 — Example(m³/m²/d) 1 Compara- Blocking rate (%) 98.5 93.0 97.8 92.4 tivePermeation flux 0.12 — 0.16 — Example (m³/m²/d) 2 Compara- Blocking rate(%) 83.9 54.3 91.3 73.3 tive Permeation flux 0.72 — 0.56 — Example(m³/m²/d) 3 Compara- Blocking rate (%) 91.5 68.7 94.5 70.6 tivePermeation flux 0.75 — 0.60 — Example (m³/m²/d) 4

As can be understood from comparison of Comparative Examples 1-2 to 1-4with Examples 1-1 to 1-2 about the results thereof, it is demonstratedthat when an aromatic ring is present as a substituent on the nitrogenof the amino group, the rate of blocking solutes such as salt becomesvery high.

Example 1-3

An aqueous solution containing 2% by weight of N-phenylethylenediamine,0.15% by weight of sodium laurylsulfate, 2% by weight of triethylamine,and 4% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.15% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. Thereafter, the resultant was dried at 120° C.for 5 minutes to form a polymer thin film (thickness: 1 μm) on theporous support membrane. Thus, a composite semipermeable membrane wasobtained.

This composite membrane was continuously operated at an operationpressure of 1.5 MPa, using raw water containing sodium hypochloritehaving a free chlorine concentration of 100 mg/L. The transitions of thepermeation flux and the salt-blocking rate of the composite membrane atthis time are shown in FIG. 1.

Comparative Example 1-5

The composite membrane obtained in Comparative Example 1-1 wascontinuously operated at an operation pressure of 1.5 MPa, using rawwater containing sodium hypochlorite having a free chlorineconcentration of 100 mg/L. The transition of the salt-blocking rate ofthe composite membrane at this time is shown in FIG. 1.

As shown by the results from FIG. 1, in Example 1-3 of the presentinvention, the initial blocking rate was able to be maintained for along time. However, in Comparative Example 1-5, the membrane wasdeteriorated by sodium hypochlorite so that the blocking rate droppedsuddenly.

Reference Example 1-1

An aqueous solution containing 3% by weight of N-benzylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.2% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 50.4%. The permeation fluxwas 0.25 m³/(m²/day). Under the same conditions, a test about ammoniumnitrate was made. As a result, the blocking rate was 45.2%.

This membrane was immersed into an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 100 mg/L. After 100 hours, testswere made under the same conditions. As a result, the rate of blockingsalt was 61.1%, and the permeation flux was 1.06 m³/(m²/day). The rateof blocking ammonium nitrate was 60.1%.

Reference Example 1-2

An aqueous solution containing 2% by weight ofN,N′-diphenylethylenediamine, 0.10% by weight of sodium laurylsulfate,2% by weight of triethylamine, 4% by weight of camphorsulfonic acid and30% by weight of acetonitrile was brought into contact with a porouspolysulfonic support membrane (average pore size on a thin film formedside: 20 nm, asymmetrical film). Thereafter, an excess of the aqueoussolution was removed. Next, an isooctane solution containing 0.5% byweight of trimesic acid chloride was brought into contact with thesurface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 67.7%. The permeation fluxwas 0.25 m³/(m²/day). Under the same conditions, a test about ammoniumnitrate was made. As a result, the blocking rate was 65.5%.

This membrane was immersed into an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 100 mg/L. After 100 hours, testswere made under the same conditions. As a result, the rate of blockingsalt was 61.3%, and the permeation flux was 0.26 m³/(m²/day). The rateof blocking ammonium nitrate was 61.8%.

Reference Example 1-3

An aqueous solution containing 3% by weight ofN,N′-dibenzylethylenediamine, 0.10% by weight of sodium laurylsulfate,3% by weight of triethylamine, 6% by weight of camphorsulfonic acid and20% by weight of acetonitrile was brought into contact with a porouspolysulfonic support membrane (average pore size on a thin film formedside: 20 nm, asymmetrical film). Thereafter, an excess of the aqueoussolution was removed. Next, an isooctane solution containing 0.2% byweight of trimesic acid chloride was brought into contact with thesurface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 80.8%. The permeation fluxwas 0.15 m³/(m²/day). Under the same conditions, a test about ammoniumnitrate was made. As a result, the blocking rate was 71.2%.

This membrane was immersed into an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 100 mg/L. After 100 hours, testswere made under the same conditions. As a result, the rate of blockingsalt was 80.2%, and the permeation flux was 0.16 m³/(m²/day). The rateof blocking ammonium nitrate was 69.6%.

Example 2-1

An aqueous solution containing 3% by weight of N-phenylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.2% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was immersed into anaqueous sodium hypochlorite solution having a free chlorineconcentration of 100 mg/L at ambient temperature for 50 hours.Thereafter, the membrane was taken out from this aqueous solution, andtested at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15% saltwater as raw water. As a result, the rate of blocking salt was 99.0%.The permeation flux was 0.82 m³/(m²·day).

Example 2-2

An aqueous solution containing 3% by weight of N-phenylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.2% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. Thereafter, the resultant was held in ahot-window drier at 120° C. for 3 minutes to form a polymer thin film(thickness: 1 μm) on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

An aqueous sodium hypochlorite solution having a free chlorineconcentration of 100 mg/L was continuously supplied to the thus obtainedcomposite semipermeable membrane at a pressure of 1.5 MPa for 15 hours.Thereafter, the membrane was tested at 25° C., pH of 7, and a pressureof 1.5 MPa, using 0.15% salt water as raw water. As a result, the rateof blocking salt was 98.8%. The permeation flux was 0.88 m³/(m²·day).

Example 2-3

An aqueous solution containing 3% by weight of N-benzylethylenediamine,0.15% by weight of sodium laurylsulfate, 3% by weight of triethylamine,and 6% by weight of camphorsulfonic acid was brought into contact with aporous polysulfonic support membrane (average pore size on a thin filmformed side: 20 nm, asymmetrical film). Thereafter, an excess of theaqueous solution was removed. Next, an isooctane solution containing0.2% by weight of trimesic acid chloride was brought into contact withthe surface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 50.4%. The permeation fluxwas 0.25 m³/(m²/day). Under the same conditions, a test about ammoniumnitrate was made. The blocking rate was 45.2%.

This membrane was immersed into an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 100 mg/L. After 100 hours, testswere made under the same conditions. As a result, the rate of blockingsalt was 61.1%. The permeation flux was 1.06 m³/(m²/day). The rate ofblocking ammonium nitrate was 60.1%.

Comparative Example 2-1

In Example 2-1, the test was made without performing the immersion intothe aqueous sodium hypochlorite solution. As a result, the rate ofblocking salt was 99.3%. The permeation flux was 0.32 m³/(m²·day). Itwas understood from comparison thereof with Example 2-1 that oxidizertreatment caused an increase in the permeation flux without lowering thesalt-blocking rate remarkably.

Comparative Example 2-2

An aqueous solution containing 3% by weight of m-phenylenediamine, 0.15%by weight of sodium laurylsulfate, 3% by weight of triethylamine, and 6%by weight of camphorsulfonic acid was brought into contact with a porouspolysulfonic support membrane (average pore size on a thin film formedside: 20 nm, asymmetrical film). Thereafter, an excess of the aqueoussolution was removed. Next, an isooctane solution containing 0.2% byweight of trimesic acid chloride was brought into contact with thesurface of the support membrane to cause an interfacial condensationpolymerization reaction. In this way, a polymer thin film (thickness: 1μm) was formed on the porous support membrane. Thus, a compositesemipermeable membrane was obtained.

The thus obtained composite semipermeable membrane was tested at 25° C.,pH of 7, and a pressure of 1.5 MPa, using 0.15% salt water as raw water.As a result, the rate of blocking salt was 99.5%. The permeation fluxwas 1.1 m³/(m²·day).

The thus obtained composite semipermeable membrane was immersed into anaqueous sodium hypochlorite solution having a free chlorineconcentration of 100 mg/L at ambient temperature for 50 hours.Thereafter, the membrane was taken out from this aqueous solution, andtested at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15% saltwater as raw water. As a result, the rate of blocking salt was 96.2%.The permeation flux was 3.5 m³/(m²·day). It was demonstrated that in thecase that m-phenylenediamine was used as the diamine component in thisway, the salt-blocking rate of the membrane was markedly lowered by thesimilar oxidizer treatment.

Comparative Example 2-3

A composite semipermeable membrane was produced in the same way as inExample 2-1 except that diamine component was changed toN-methylethylenediamine. Without performing any oxidizer treatment, awater treatment test was made. As a result, the rate of blocking saltwas 83.9%, and the permeation flux was 0.72 m³/(m²·day). The thusobtained composite semipermeable membrane was immersed into an aqueoussodium hypochlorite solution having a free chlorine concentration of 100mg/L at ambient temperature for 100 hours. Thereafter, the membrane wastaken out from this aqueous solution, and tested at 25° C., pH of 7, anda pressure of 1.5 MPa, using 0.15% salt water as raw water. As a result,the rate of blocking salt was 91.3%. The permeation flux was 0.56m³/(m²·day). In the case that N-methylethyldiamine was used in this way,the salt-blocking rate was slightly increased but the water flux waslowered by the similar oxidizer treatment.

Example 2-4

The composite semipermeable membrane obtained in Example 2-2 wasimmersed at 40° C. for 3 hours in a solution wherein 0.5% by weight ofmagnesium chloride was added to an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 1000 mg/L. Thereafter, thesemipermeable membrane was taken out from the aqueous solution, and atest was made at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15%salt water as raw water. As a result, the rate of blocking salt was92.52%. The permeation flux was 0.71 m³/(m²·day).

Example 2-5

The composite semipermeable membrane obtained in Example 2-2 wasimmersed at 40° C. for 3 hours into a solution wherein 0.5% by weight ofmagnesium nitrate was added to an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 1000 mg/L. Thereafter, thesemipermeable membrane was taken out from the aqueous solution , and atest was made at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15%salt water as raw water. As a result, the rate of blocking salt was92.28%. The permeation flux was 0.65 m³/(m²·day).

Example 2-6

The composite semipermeable membrane obtained in Example 2-2 wasimmersed at 40° C. for 3 hours in a solution wherein 0.5% by weight ofpotassium chloride was added to an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 1000 mg/L. Thereafter, thesemipermeable membrane was taken out from the aqueous solution, and atest was made at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15%salt water as raw water. As a result, the rate of blocking salt was91.86%. The permeation flux was 0.62 m³/(m²·day).

Example 2-7

The composite semipermeable membrane obtained in Example 2-2 wasimmersed at 40° C. for 3 hours into a solution wherein 0.5% by weight ofcalcium chloride was added to an aqueous sodium hypochlorite solutionhaving a free chlorine concentration of 1000 mg/L. Thereafter, thesemipermeable membrane was taken out from the aqueous solution, and atest was made at 25° C., pH of 7, and a pressure of 1.5 MPa, using 0.15%salt water as raw water. As a result, the rate of blocking salt was92.21%. The permeation flux was 0.65 m³/(m²·day).

Reference Example 2-1

In Examples 2-4, the semipermeable membrane was immersed into an aqueoussodium hypochlorite solution 40° C. in temperature without adding anyinorganic salt. In the same way, tests were made. As a result, the rateof blocking salt was 92%. The permeation flux was 0.5 m³/(m²·day). Itwas understood from comparison with Example 2-4 that the salt-blockingrate was not markedly lowered and the permeation flux was increased byoxidizer treatment based on the aqueous oxidizer solution containing themetal salt.

INDUSTRIAL APPLICABILITY

The composite semipermeable membrane of the present invention issuitable for the production of ultra pure water, removal of salts fromsaline water or sea water, and so on, and makes it possible to removeand recollect contaminant sources or effective materials from dirtythings, which are causes of the generation of environmental pollution,such as dyeing waste liquid and electrodeposition paint waste liquid,and contribute to the closing of the waster liquid. The membrane can beused for concentration of effective components, and so on for food etc.In particular, the water-treating method in the present invention can besuitably used for purposes producing advantages such that thecontamination of the membrane is suppressed by incorporating an oxidizerhaving a sterilizing effect into raw water. Examples thereof includesterilization of an aseptic water system, removal of activated carbonfrom a system for producing drinking water, disposal of waste of washingliquid for containers in the food industry, and a system for cleaning upwater in a pool.

1. A composite semipermeable membrane comprising a porous supportmembrane and a thin film formed thereon, said thin film comprising apolyamide based resin constituted by a unit obtained by condensationreaction of a diamine component with a non-hetero aromaticpolyfunctional acid halide having 2 or more valences, said unit beingrepresented by the following general formulas (I) and/or (II), saidpolyamide based resin comprising said unit at a ratio of 50% or more bymole:

wherein R₁₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group,and R₁₂ and R₁₃ each independently represent anaromatic hydrocarbon group which may have a substituent, or a hydrogenatom, at least one of R₁₂ or R₁₃ represents an aromatic hydrocarbongroup which may have a substituent, and R₁₄ represents a bivalentnon-hetero aromatic group which may have a substituent, and

wherein R₂₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₂₂ and R₂₃ each independently represent anaromatic hydrocarbon group which may have a substituent, or a hydrogenatom, at least one of R₂₂ or R₂₃ represents an aromatic hydrocarbongroup which may have a substituent, and R₂₄ represents a trivalentnon-hetero aromatic group which may have a substituent.
 2. The compositesemipermeable membrane according to claim 1, wherein the polyamide basedresin comprises the unit at a ratio of 80% or more by mole.
 3. Acomposite semipermeable membrane comprising a porous support membraneand a thin film formed thereon, said thin film comprising a polyamidebased resin constituted by a unit obtained by condensation reaction of adiamine component with a non-hetero aromatic polyfunctional acid halidehaving 2 or more valences, said unit being represented by the followinggeneral formulas (Ia) and/or (IIa), said polyamide based resincomprising said unit at a ratio of 50% or more by mole:

wherein R₃₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR—, wherein R represents a hydrogen atomor a lower alkyl group, R₃₂ and R₃₃ each independently represent aphenyl group, or a hydrogen atom, at least one of R₃₂ or R₃₃ representsa phenyl group, and R₃₄ represents a bivalent aromatic group which mayhave a substituent, and

wherein R₄₁ represents an alkylene group which has 2 to 10 carbon atomsand may contain —O—, —S—, or —NR— wherein R represents a hydrogen atomor a lower alkyl group, R₄₂ and R₄₃ each independently represent aphenyl group, or a hydrogen atom, at least one of R₄₂ or R₄₃ representsa phenyl group, and R₄₄ represents a trivalent non-hetero aromatic groupwhich may have a substituent.
 4. The composite semipermeable membraneaccording to claim 3, wherein the polyamide based resin comprises theunit at a ratio of 80% or more by mole.
 5. A method for treating acomposite semipermeable membrane, comprising bringing a compositesemipermeable membrane into contact with an aqueous oxidizer solutionalong with a metal salt, said composite semipermeable membranecomprising a porous support membrane and a thin film formed thereon,said thin film comprising a polyamide-derived resin comprising at aratio of 50% or more by mole a constituent unit obtained by condensationreaction of a diamine component with an aromatic polyfunctional acidhalide having 2 or more valences, said unit having the formula:

wherein R¹ represents a C₂₋₁₀ alkylene group which may contain —O—, —S—,or —NR—, wherein R represents a hydrogen atom or a lower alkyl group; R²and R₃ each independently represent an aromatic hydrocarbon group whichmay have a substituent, or a hydrogen atom, at least one of R² or R₃represents an aromatic hydrocarbon group which may have a substituent;and R₄ represents a bivalent aromatic organic group which may have asubstituent, a trivalent aromatic organic group to which —CO— isattached; or a residue group of a polyfunctional acid halide having 2 ormore valences.
 6. The method according to claim 5, wherein the contactstep is performed by immersing the composite semipermeable membrane intothe aqueous oxidizer solution under normal pressure.
 7. The methodaccording to claim 5, wherein the contact step is performed bytransmitting the aqueous oxidizer solution into the compositesemipermeable membrane under applied pressure.
 8. The method accordingto claim 5, wherein the aqueous oxidizer solution is an aqueous sodiumhypochlorite solution.
 9. A composite semipermeable membrane which isproduced by a production process according to claim
 5. 10. Awater-treating method comprising adding a fungicide to raw watercontaining salts and/or organic substances; and subjecting the raw waterto membrane-separation treatment with a composite semipermeable membraneof claim 9 to obtain permeation water wherein the salts and/or theorganic substances are sufficiently removed in practice.
 11. Thewater-treating method according to claim 10, wherein the fungicide is ahypochlorite.
 12. The water-treating method according to claim 10,wherein the fungicide is also present, at a concentration having asufficient sterilizing effect, in the permeation water through themembrane-separation treatment.
 13. The water-treating method accordingto claim 10, wherein the raw water is discharged water after a drinkingwater container is washed with a washing liquid.
 14. The methodaccording to claim 5, wherein the metal salt is selected from the groupconsisting of alkali metal salts, alkali earth metal salts, andtransition metal salts.
 15. The method according to claim 5, wherein themetal salt is selected from the group consisting of lithium chloride,potassium chloride, magnesium chloride, magnesium nitrate, calciumnitrate, iron chloride, copper chloride, and calcium chloride.
 16. Themethod according to claim 5, wherein the aromatic polyfunctional acidhalide is a non-hetero compound, and R⁴ represents a non-hetero aromaticorganic group.
 17. The method according to claim 5, wherein the metalsalt is selected from the group consisting of alkali earth metal saltsand transition metal salts.
 18. The method according to claim 17,wherein the metal salt is selected from the group consisting ofmagnesium chloride, magnesium nitrate, calcium nitrate, iron chloride,copper chloride, and calcium chloride.
 19. The method according to claim17, wherein the metal salt is selected from the group consisting ofmagnesium chloride, magnesium nitrate, and calcium chloride.
 20. Acomposite semipermeable membrane comprising a porous support membraneand a thin film formed thereon, said thin film comprising apolyamide-derived resin constituted by a unit obtained by condensationreaction of a diamine component with a non-hetero aromaticpolyfunctional acid halide having 2 or more valences, saidpolyamide-derived resin comprising said unit at a ratio of 50% or moreby mole, said unit having the formula:

wherein R¹ represents a C₂₋₁₀ alkylene group which may contain —O—, —S—,or —NR—, wherein R represents a hydrogen atom or a lower alkyl group; R²and R³ each independently represent an aromatic hydrocarbon group whichmay have a substituent, or a hydrogen atom, at least one of R₂ or R₃represents an aromatic hydrocarbon group which may have a substituent;and R₄ represents a bivalent non-hetero aromatic organic group which mayhave a substituent, a trivalent aromatic organic group to which —CO— isattached; or a residue group of a polyfunctional acid halide having 2 ormore valences.
 21. The composite semipermeable membrane according toclaim 20, wherein the aromatic hydrocarbon is a phenyl group.
 22. Awater-treating method comprising adding a fungicide to raw watercontaining salts and/or organic substances; and subjecting the raw waterto membrane-separation treatment with the composite semipermeablemembrane of claim 20 to obtain permeation water wherein the salts and/orthe organic substances are sufficiently removed in practice.
 23. Thewater-treating method according to claim 22, wherein the fungicide is ahypochiorite.
 24. the water-treating method according to claim 22,wherein the fungicide is also present, at a concentration having asufficient sterilizing effect, in the permeation water through themembrane-separation treatment.
 25. The water-treating method accordingto claim 22, wherein the raw water is discharged water after a drinkingwater container is washed with a washing liquid.
 26. The compositesemipermeable membrane according to claim 20, wherein the polyamidebased. resin comprises the unit at a ratio of 80% or more by mole.